Collaborative Research: Using Herbivorous Insect Genomes for Crop Tracking

The goal of this project is to conduct a research study of the histories of crop range expansions by Indigenous North Americans. The domestication and assisted dispersal of plant and animal species by humans has dramatically changed global ecosystems, but the direct study of historical domestication of some species is often limited by methodological challenges.

For example, while the ancestral ranges and subsequent range extensions of some North American crops are well studied, others remain relatively inaccessible. This research explores whether historical signals of range expansion captured within the genomes of insects, parasitic on focal crop plants, can be used as proxies for the histories of the plants themselves.

This research provides a general proof of principle for using parasitic insects to study demographic histories of their plant hosts, but also specifically tests hypotheses for the pre-domestication ranges and histories of expansion for three crops of the Eastern Agricultural Complex (EAC): Common sunflower, Jerusalem artichoke, and sumpweed. This research results in the training of graduate and undergraduate students, lead to design and implementation of new materials for public outreach demonstrations, and bring about a large public science event focused on the Indigenous agriculture.

This research uses information captured in the genomes of specialist insects to reconstruct signatures of past cultivation and subsequent range expansions for three North American crops; the work addresses the questions: where did these plants grow before they were first used as crops, and where (and when) were they subsequently moved by people? Common sunflower, Jerusalem artichoke, and sumpweed are known to have been cultivated by Indigenous North Americans as part of the Eastern Agricultural Complex, but beyond this there is great variance in how much is known about their respective ancestral ranges and subsequent patterns of range extensions.

Two fly species in the North American genus Strauzia feed on, respectively, common sunflower and Jerusalem artichoke, while caterpillars of the slender flower moth are specialist herbivores on sumpweed. The researchers are making large collections of these three insect parasites from across their host plants’ ranges in the North America, and then interrogating their genomes for signals of historical population size changes and the direction and timing of range expansions.

A general prediction is that the region of highest genetic diversity for each insect will correspond to the historical boundaries of the EAC, implicating this area as having been part of the ancestral range for each plant. A second expectation is that tests of demographic scenarios using genetic data will best support relatively recent range expansions, radiating out from their respective native range(s).

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.